Alert archive / South Dakota / Winter Storm Watches in 2017

Winter Storm Watch 3, NWS Sioux Falls, SD

February 21, 20174 states

NWS Sioux Falls, SD issued this winter storm watch at Feb 21, 2017, 3:59 PM CST for 4 states. It took effect at Feb 23, 2017, 12:00 PM CST. It was in force for .

The area

The counties it named.

The facts

Issued
Feb 21, 2017, 3:59 PM CST (21:59 UTC)
In effect from
Feb 23, 2017, 12:00 PM CST
Expired
Feb 23, 2017, 4:14 AM CST
In force
Issued by
NWS Sioux Falls, SD
All 45 counties

Buena Vista County, IA, Cherokee County, IA, Clay County, IA, Dickinson County, IA, Ida County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Sioux County, IA, Woodbury County, IA, Cottonwood County, MN, Jackson County, MN, Lincoln County, MN, Lyon County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Rock County, MN, Dakota County, NE, Dixon County, NE, Aurora County, SD, Beadle County, SD, Bon Homme County, SD, Brookings County, SD, Brule County, SD, Charles Mix County, SD, Clay County, SD, Davison County, SD, Douglas County, SD, Gregory County, SD, Hanson County, SD, Hutchinson County, SD, Jerauld County, SD, Kingsbury County, SD, Lake County, SD, Lincoln County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Sanborn County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 16 km from the middle of the area, began a volume at 21:58 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Aberdeen, SD (KABR), launched 12:00Z, 10.0 hours before the alert went out and 202 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Aberdeen, SD at 12:00Z on 2017-02-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Aberdeen, SD at 12:00Z on 2017-02-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 317 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1997 m above ground
0-6 km bulk shear
67 kt
0-1 km storm-relative helicity
317 m²/s²
0-3 km storm-relative helicity
337 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

333 
WWUS43 KFSD 212159
WSWFSD

URGENT - WINTER WEATHER MESSAGE
National Weather Service Sioux Falls SD
359 PM CST Tue Feb 21 2017

IAZ001>003-012>014-020>022-MNZ071-072-080-081-089-090-097-098-
NEZ013-SDZ040-050-054>071-220600-
/O.NEW.KFSD.WS.A.0003.170224T0000Z-170225T0000Z/
Lyon IA-Osceola-Dickinson-Sioux-O'Brien-Clay IA-Plymouth-Cherokee-
Buena Vista-Lincoln MN-Lyon MN-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-Dixon-Brookings-Gregory-Miner-Lake-Moody-Brule-
Aurora-Davison-Hanson-McCook-Minnehaha-Charles Mix-Douglas-
Hutchinson-Turner-Lincoln SD-Bon Homme-Yankton-Clay SD-Union-
359 PM CST Tue Feb 21 2017

...WINTER STORM WATCH IN EFFECT FROM THURSDAY EVENING THROUGH
FRIDAY AFTERNOON...

The National Weather Service in Sioux Falls has issued a Winter
Storm Watch, which is in effect from Thursday evening through
Friday afternoon. 

* TIMING...Rain will begin mixing with snow midday Thursday, then
  change entirely to snowfall Thursday evening. Snow will continue
  into Friday, before gradually tapering off in the afternoon.

* ACCUMULATIONS...Storm total snow accumulations of 6 to 10 
  inches are possible.

* WIND AND VISIBILITY...Winds will increase from the north around
  20 to 30 mph on Thursday night and Friday. Visibility is
  expected to be reduced to less than a half mile at times while
  snow is falling.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is a potential for significant
snow...sleet...or ice accumulations that may impact travel.
Continue to monitor the latest forecasts.

&&

$$
5 follow-up statements
103 
WWUS43 KFSD 220411
WSWFSD

URGENT - WINTER WEATHER MESSAGE
National Weather Service Sioux Falls SD
1011 PM CST Tue Feb 21 2017

IAZ001>003-012>014-020>022-MNZ071-072-080-081-089-090-097-098-
NEZ013-SDZ040-050-054>071-221215-
/O.CON.KFSD.WS.A.0003.170224T0000Z-170225T0000Z/
Lyon IA-Osceola-Dickinson-Sioux-O'Brien-Clay IA-Plymouth-Cherokee-
Buena Vista-Lincoln MN-Lyon MN-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-Dixon-Brookings-Gregory-Miner-Lake-Moody-Brule-
Aurora-Davison-Hanson-McCook-Minnehaha-Charles Mix-Douglas-
Hutchinson-Turner-Lincoln SD-Bon Homme-Yankton-Clay SD-Union-
1011 PM CST Tue Feb 21 2017

...WINTER STORM WATCH REMAINS IN EFFECT FROM THURSDAY EVENING
THROUGH FRIDAY AFTERNOON...

* TIMING...Rain will begin mixing with snow midday Thursday, 
  then change entirely to snowfall Thursday evening. Snow will 
  continue into Friday, before gradually tapering off in the 
  afternoon. 

* ACCUMULATIONS...Storm total snow accumulations of 6 to 10 
  inches are possible. 

* WIND AND VISIBILITY...Winds will increase from the north 
  around 20 to 30 mph on Thursday night and Friday. Visibility 
  is expected to be reduced to less than a half mile at times 
  while snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is a potential for significant
snow...sleet...or ice accumulations that may impact travel.
Continue to monitor the latest forecasts.

&&

$$
759 
WWUS43 KFSD 220937
WSWFSD

URGENT - WINTER WEATHER MESSAGE
National Weather Service Sioux Falls SD
337 AM CST Wed Feb 22 2017

SDZ052-221745-
/O.EXB.KFSD.WS.A.0003.170223T1800Z-170225T0000Z/
Jerauld-
337 AM CST Wed Feb 22 2017

...WINTER STORM WATCH IN EFFECT FROM THURSDAY AFTERNOON THROUGH
FRIDAY AFTERNOON...

The National Weather Service in Sioux Falls has issued a Winter
Storm Watch, which is in effect from Thursday afternoon through
Friday afternoon. 

* TIMING...Snow will spread into the area by midday Thursday, then
  continue heavy at times Thursday night into Friday. Snow should
  diminish Friday afternoon.

* ACCUMULATIONS...Storm total snow accumulations of 6 to 12 inches
  are likely, with amounts in excess of 12 inches possible.

* WIND AND VISIBILITY...Winds will increase from the north 
  around 20 to 35 mph on Thursday night and Friday. Visibility 
  is expected to be reduced to less than a half mile at times 
  while snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is a potential for significant
snow...sleet...or ice accumulations that may impact travel.
Continue to monitor the latest forecasts.

&&

$$

IAZ031-032-NEZ014-221745-
/O.EXB.KFSD.WS.A.0003.170224T0000Z-170225T0600Z/
Woodbury-Ida-Dakota-
337 AM CST Wed Feb 22 2017

...WINTER STORM WATCH IN EFFECT FROM THURSDAY EVENING THROUGH
FRIDAY EVENING...

The National Weather Service in Sioux Falls has issued a Winter
Storm Watch, which is in effect from Thursday evening through
Friday evening. 

* TIMING...Rain will change to snow Thursday night, with snow
  continuing heavy at times Friday. Snow should diminish Friday
  night. 

* ACCUMULATIONS...Storm total snow accumulations of 6 inches are
  possible.

* WIND AND VISIBILITY...Winds will increase from the north around
  20 to 35 mph Thursday night through Friday evening. Visibility
  is expected to be reduced to less than a half mile at times
  while snow is falling.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is a potential for significant
snow...sleet...or ice accumulations that may impact travel.
Continue to monitor the latest forecasts.

&&

$$

SDZ038-039-053-221745-
/O.EXA.KFSD.WS.A.0003.170224T0000Z-170225T0000Z/
Beadle-Kingsbury-Sanborn-
337 AM CST Wed Feb 22 2017

...WINTER STORM WATCH IN EFFECT FROM THURSDAY EVENING THROUGH
FRIDAY AFTERNOON...

The National Weather Service in Sioux Falls has issued a Winter
Storm Watch, which is in effect from Thursday evening through
Friday afternoon. 

* TIMING...Snow will spread into the area Thursday afternoon, then
  continue heavy at times Thursday night into Friday. Snow should
  diminish Friday afternoon.

* ACCUMULATIONS...Storm total snow accumulations of 6 to 12 inches
  are likely, with amounts in excess of 12 inches possible.

* WIND AND VISIBILITY...Winds will increase from the north 
  around 25 to 35 mph on Thursday night and Friday. Visibility 
  is expected to be reduced to less than a half mile at times 
  while snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is a potential for significant
snow...sleet...or ice accumulations that may impact travel.
Continue to monitor the latest forecasts.

&&

$$

SDZ050-057-058-063-064-221745-
/O.EXT.KFSD.WS.A.0003.170223T1800Z-170225T0000Z/
Gregory-Brule-Aurora-Charles Mix-Douglas-
337 AM CST Wed Feb 22 2017

...WINTER STORM WATCH NOW IN EFFECT FROM THURSDAY AFTERNOON
THROUGH FRIDAY AFTERNOON...

* TIMING...Snow will spread into the area by midday Thursday, then
  continue heavy at times Thursday night into Friday. Snow should
  diminish Friday afternoon.

* ACCUMULATIONS...Storm total snow accumulations of 6 to 12 inches
  are likely, with amounts in excess of 12 inches possible. 

* WIND AND VISIBILITY...Winds will increase from the north 
  around 20 to 35 mph on Thursday night and Friday. Visibility 
  is expected to be reduced to less than a half mile at times 
  while snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is a potential for significant
snow...sleet...or ice accumulations that may impact travel.
Continue to monitor the latest forecasts.

&&

$$

IAZ001>003-012>014-020>022-MNZ071-072-080-081-089-090-097-098-
221745-
/O.EXT.KFSD.WS.A.0003.170224T0000Z-170225T0600Z/
Lyon IA-Osceola-Dickinson-Sioux-O'Brien-Clay IA-Plymouth-Cherokee-
Buena Vista-Lincoln MN-Lyon MN-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-
337 AM CST Wed Feb 22 2017

...WINTER STORM WATCH NOW IN EFFECT FROM THURSDAY EVENING THROUGH
FRIDAY EVENING...

* TIMING...A mix of rain and snow Thursday afternoon will change
  to all snow Thursday evening. Snow will continue heavy at times
  Thursday night and Friday, before gradually tapering off Friday
  night.

* ACCUMULATIONS...Storm total snow accumulations of 6 to 12 inches
  are likely, with amounts in excess of 12 inches possible. 

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 30 mph Thursday night, with gusts over 40 mph possible on
  Friday into Friday evening. Visibility is expected to be reduced
  to less than a half mile at times while snow is falling.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is a potential for significant
snow...sleet...or ice accumulations that may impact travel.
Continue to monitor the latest forecasts.

&&

$$

NEZ013-SDZ040-054>056-059>062-065>071-221745-
/O.CON.KFSD.WS.A.0003.170224T0000Z-170225T0000Z/
Dixon-Brookings-Miner-Lake-Moody-Davison-Hanson-McCook-Minnehaha-
Hutchinson-Turner-Lincoln SD-Bon Homme-Yankton-Clay SD-Union-
337 AM CST Wed Feb 22 2017

...WINTER STORM WATCH REMAINS IN EFFECT FROM THURSDAY EVENING
THROUGH FRIDAY AFTERNOON...

* TIMING...A mix of rain and snow Thursday afternoon will change
  to all snow Thursday evening. Snow will continue heavy at times
  Thursday night and Friday, before gradually tapering off Friday
  evening.

* ACCUMULATIONS...Storm total snow accumulations of 6 to 12 inches
  are likely, with amounts in excess of 12 inches possible. 

* WIND AND VISIBILITY...Winds will increase from the north 
  around 20 to 35 mph on Thursday night and Friday. Visibility 
  is expected to be reduced to less than a half mile at times 
  while snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is a potential for significant
snow...sleet...or ice accumulations that may impact travel.
Continue to monitor the latest forecasts.

&&

$$
562 
WWUS43 KFSD 222122
WSWFSD

URGENT - WINTER WEATHER MESSAGE
National Weather Service Sioux Falls SD
322 PM CST Wed Feb 22 2017

SDZ050-052-057-058-063-064-230530-
/O.CAN.KFSD.WS.A.0003.170223T1800Z-170225T0000Z/
/O.NEW.KFSD.BZ.A.0001.170223T1800Z-170225T0000Z/
Gregory-Jerauld-Brule-Aurora-Charles Mix-Douglas-
322 PM CST Wed Feb 22 2017

...BLIZZARD WATCH IN EFFECT FROM THURSDAY AFTERNOON THROUGH
FRIDAY AFTERNOON...
...WINTER STORM WATCH IS CANCELLED...

The National Weather Service in Sioux Falls has issued a Blizzard
Watch, which is in effect from Thursday afternoon through Friday
afternoon. The Winter Storm Watch has been cancelled. 

* TIMING...Snow will spread into the area by midday Thursday, then continue
  heavy at times Thursday night into Friday. Snow should diminish
  Friday afternoon.

* ACCUMULATIONS...Storm total snow accumulations of 6 to 12 
  inches are likely, with amounts in excess of 12 inches 
  possible. 

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 35 mph by Thursday afternoon into Friday. Visibility is
  expected to be reduced to less than a quarter of a mile at 
  times while snow is falling. 


PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Blizzard Watch means there is a potential for falling and/or
blowing snow with strong winds and extremely poor visibilities.
This can lead to whiteout conditions and make travel very
dangerous.

&&

$$

NEZ013-SDZ053>056-059>062-065>071-230530-
/O.CAN.KFSD.WS.A.0003.170224T0000Z-170225T0000Z/
/O.NEW.KFSD.BZ.A.0001.170224T0000Z-170225T0000Z/
Dixon-Sanborn-Miner-Lake-Moody-Davison-Hanson-McCook-Minnehaha-
Hutchinson-Turner-Lincoln SD-Bon Homme-Yankton-Clay SD-Union-
322 PM CST Wed Feb 22 2017

...BLIZZARD WATCH IN EFFECT FROM THURSDAY EVENING THROUGH FRIDAY
AFTERNOON...
...WINTER STORM WATCH IS CANCELLED...

The National Weather Service in Sioux Falls has issued a Blizzard
Watch, which is in effect from Thursday evening through Friday
afternoon. The Winter Storm Watch has been cancelled. 

* TIMING...A possible mix of rain and snow on Thursday afternoon
  will change to all snow by early Thursday evening. Snow will 
  continue heavy at times Thursday night and Friday, before 
  gradually tapering off Friday evening.

* ACCUMULATIONS...Storm total snow accumulations of 6 to 12 
  inches are likely, with amounts in excess of 12 inches 
  possible. 

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 35 mph on Thursday night and Friday. Visibility is
  expected to be reduced to less than a quarter of a mile at 
  times while snow is falling. 


PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Blizzard Watch means there is a potential for falling and/or
blowing snow with strong winds and extremely poor visibilities.
This can lead to whiteout conditions and make travel very
dangerous.

&&

$$

IAZ001>003-012>014-020>022-MNZ071-072-080-081-089-090-097-098-
NEZ014-230530-
/O.CAN.KFSD.WS.A.0003.170224T0000Z-170225T0600Z/
/O.NEW.KFSD.BZ.A.0001.170224T0000Z-170225T0600Z/
Lyon IA-Osceola-Dickinson-Sioux-O'Brien-Clay IA-Plymouth-Cherokee-
Buena Vista-Lincoln MN-Lyon MN-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-Dakota-
322 PM CST Wed Feb 22 2017

...BLIZZARD WATCH IN EFFECT FROM THURSDAY EVENING THROUGH FRIDAY
EVENING...
...WINTER STORM WATCH IS CANCELLED...

The National Weather Service in Sioux Falls has issued a Blizzard
Watch, which is in effect from Thursday evening through Friday
evening. The Winter Storm Watch has been cancelled. 

* TIMING...A brief mix of rain and snow Thursday afternoon will
  change to all snow by early Thursday evening. Snow will 
  continue heavy at times Thursday night and Friday, before 
  gradually tapering off Friday night.

* ACCUMULATIONS...Storm total snow accumulations of 6 to 12 
  inches are likely, with amounts in excess of 12 inches 
  possible. 

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 35 mph Thursday night, with gusts over 45 mph possible on
  Friday into Friday evening. Visibility is expected to be reduced
  to less than a quarter of a mile at times while snow is falling.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Blizzard Watch means there is a potential for falling and/or
blowing snow with strong winds and extremely poor visibilities.
This can lead to whiteout conditions and make travel very
dangerous.

&&

$$

SDZ038>040-230530-
/O.CON.KFSD.WS.A.0003.170224T0000Z-170225T0000Z/
Beadle-Kingsbury-Brookings-
322 PM CST Wed Feb 22 2017

...WINTER STORM WATCH REMAINS IN EFFECT FROM THURSDAY EVENING
THROUGH FRIDAY AFTERNOON...

* TIMING...snow will develop across the area and become heavy at
  times by Thursday night and Friday, before gradually tapering 
  off Friday evening.


* ACCUMULATIONS...Storm total snow accumulations of 6 to 10 inches
  are likely.

* WIND AND VISIBILITY...Winds will increase from the north around
  20 to 35 mph by Thursday afternoon into Friday. Visibility is 
  expected to be reduced to less than a half mile at times while 
  snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is a potential for significant
snow...sleet...or ice accumulations that may impact travel.
Continue to monitor the latest forecasts.

&&

$$

IAZ031-032-230530-
/O.CON.KFSD.WS.A.0003.170224T0000Z-170225T0600Z/
Woodbury-Ida-
322 PM CST Wed Feb 22 2017

...WINTER STORM WATCH REMAINS IN EFFECT FROM THURSDAY EVENING
THROUGH FRIDAY EVENING...

* TIMING...Rain will change to snow Thursday night, with snow 
  continuing heavy at times Friday. Snow should diminish Friday 
  night. 

* ACCUMULATIONS...Storm total snow accumulations of 6 to 10 inches
  are possible. 

* WIND AND VISIBILITY...Winds will increase from the north 
  around 20 to 35 mph Thursday night through Friday evening. 
  Visibility is expected to be reduced to less than a half mile 
  at times while snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is a potential for significant
snow...sleet...or ice accumulations that may impact travel.
Continue to monitor the latest forecasts.

&&

$$
164 
WWUS43 KFSD 230257
WSWFSD

URGENT - WINTER WEATHER MESSAGE
National Weather Service Sioux Falls SD
857 PM CST Wed Feb 22 2017

SDZ050-052-057-058-063-064-231100-
/O.CON.KFSD.BZ.A.0001.170223T1800Z-170225T0000Z/
Gregory-Jerauld-Brule-Aurora-Charles Mix-Douglas-
857 PM CST Wed Feb 22 2017

...BLIZZARD WATCH REMAINS IN EFFECT FROM THURSDAY AFTERNOON
THROUGH FRIDAY AFTERNOON...

* TIMING...Snow will spread into the area by midday Thursday, 
  then continue heavy at times Thursday night into Friday. Snow 
  should diminish Friday afternoon. 

* ACCUMULATIONS...Storm total snow accumulations of 6 to 12 
  inches are likely, with amounts in excess of 12 inches 
  possible. 

* WIND AND VISIBILITY...Winds will increase from the north 
  around 25 to 35 mph by Thursday afternoon into Friday. 
  Visibility is expected to be reduced to less than a quarter of 
  a mile at times while snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Blizzard Watch means there is a potential for falling and/or
blowing snow with strong winds and extremely poor visibilities.
This can lead to whiteout conditions and make travel very
dangerous.

&&

$$

NEZ013-SDZ053>056-059>062-065>071-231100-
/O.CON.KFSD.BZ.A.0001.170224T0000Z-170225T0000Z/
Dixon-Sanborn-Miner-Lake-Moody-Davison-Hanson-McCook-Minnehaha-
Hutchinson-Turner-Lincoln SD-Bon Homme-Yankton-Clay SD-Union-
857 PM CST Wed Feb 22 2017

...BLIZZARD WATCH REMAINS IN EFFECT FROM THURSDAY EVENING THROUGH
FRIDAY AFTERNOON...

* TIMING...A possible mix of rain and snow on Thursday afternoon 
  will change to all snow by early Thursday evening. Snow will 
  continue heavy at times Thursday night and Friday, before 
  gradually tapering off Friday evening. 

* ACCUMULATIONS...Storm total snow accumulations of 6 to 12 
  inches are likely, with amounts in excess of 12 inches 
  possible. 

* WIND AND VISIBILITY...Winds will increase from the north 
  around 25 to 35 mph on Thursday night and Friday. Visibility 
  is expected to be reduced to less than a quarter of a mile at 
  times while snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Blizzard Watch means there is a potential for falling and/or
blowing snow with strong winds and extremely poor visibilities.
This can lead to whiteout conditions and make travel very
dangerous.

&&

$$

IAZ001>003-012>014-020>022-MNZ071-072-080-081-089-090-097-098-
NEZ014-231100-
/O.CON.KFSD.BZ.A.0001.170224T0000Z-170225T0600Z/
Lyon IA-Osceola-Dickinson-Sioux-O'Brien-Clay IA-Plymouth-Cherokee-
Buena Vista-Lincoln MN-Lyon MN-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-Dakota-
857 PM CST Wed Feb 22 2017

...BLIZZARD WATCH REMAINS IN EFFECT FROM THURSDAY EVENING THROUGH
FRIDAY EVENING...

* TIMING...A brief mix of rain and snow Thursday afternoon will 
  change to all snow by early Thursday evening. Snow will 
  continue heavy at times Thursday night and Friday, before 
  gradually tapering off Friday night. 

* ACCUMULATIONS...Storm total snow accumulations of 6 to 12 
  inches are likely, with amounts in excess of 12 inches 
  possible. 

* WIND AND VISIBILITY...Winds will increase from the north 
  around 25 to 35 mph Thursday night, with gusts over 45 mph 
  possible on Friday into Friday evening. Visibility is expected 
  to be reduced to less than a quarter of a mile at times while 
  snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Blizzard Watch means there is a potential for falling and/or
blowing snow with strong winds and extremely poor visibilities.
This can lead to whiteout conditions and make travel very
dangerous.

&&

$$

SDZ038>040-231100-
/O.CON.KFSD.WS.A.0003.170224T0000Z-170225T0000Z/
Beadle-Kingsbury-Brookings-
857 PM CST Wed Feb 22 2017

...WINTER STORM WATCH REMAINS IN EFFECT FROM THURSDAY EVENING
THROUGH FRIDAY AFTERNOON...

* TIMING...Snow will develop across the area and become heavy at 
times by Thursday night and Friday, before gradually tapering 
off Friday evening. 

* ACCUMULATIONS...Storm total snow accumulations of 6 to 10 
  inches are likely. 

* WIND AND VISIBILITY...Winds will increase from the north 
  around 20 to 35 mph by Thursday afternoon into Friday. 
  Visibility is expected to be reduced to less than a half mile 
  at times while snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is a potential for significant
snow...sleet...or ice accumulations that may impact travel.
Continue to monitor the latest forecasts.

&&

$$

IAZ031-032-231100-
/O.CON.KFSD.WS.A.0003.170224T0000Z-170225T0600Z/
Woodbury-Ida-
857 PM CST Wed Feb 22 2017

...WINTER STORM WATCH REMAINS IN EFFECT FROM THURSDAY EVENING
THROUGH FRIDAY EVENING...

* TIMING...Rain will change to snow Thursday night, with snow 
  continuing heavy at times Friday. Snow should diminish Friday 
  night. 

* ACCUMULATIONS...Storm total snow accumulations of 6 to 10 
  inches are possible. 

* WIND AND VISIBILITY...Winds will increase from the north 
  around 20 to 35 mph Thursday night through Friday evening. 
  Visibility is expected to be reduced to less than a half mile 
  at times while snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is a potential for significant
snow...sleet...or ice accumulations that may impact travel.
Continue to monitor the latest forecasts.

&&

$$
735 
WWUS43 KFSD 231014
WSWFSD

URGENT - WINTER WEATHER MESSAGE
National Weather Service Sioux Falls SD
414 AM CST Thu Feb 23 2017

NEZ013-SDZ056-062-067-070-071-231815-
/O.UPG.KFSD.BZ.A.0001.170224T0000Z-170225T0000Z/
/O.NEW.KFSD.BZ.W.0001.170224T0000Z-170225T0000Z/
Dixon-Moody-Minnehaha-Lincoln SD-Clay SD-Union-
414 AM CST Thu Feb 23 2017

...BLIZZARD WARNING IN EFFECT FROM 6 PM THIS EVENING TO 6 PM CST
FRIDAY...

The National Weather Service in Sioux Falls has issued a Blizzard
Warning, which is in effect from 6 PM this evening to 6 PM CST
Friday. The Blizzard Watch is no longer in effect. 

* TIMING...A possible mix of rain and snow this afternoon will
  change to all snow by early this evening. Snow will continue
  heavy at times Thursday night and Friday morning, before
  gradually tapering off Friday afternoon.

* ACCUMULATIONS...Storm total snow accumulations averaging 6 to 12
  inches are likely, with the heaviest amounts expected south of
  Highway 18 in northwest Iowa and extreme southeast South Dakota.

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 35 mph tonight and Friday, with gusts to near 40 mph at
  times. Visibility will be reduced to less than a quarter mile at
  times, especially while snow is falling.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Blizzard Warning means severe winter weather conditions are
expected or occurring. Falling and blowing snow with strong winds
and poor visibilities are likely. This will lead to whiteout
conditions...making travel extremely dangerous. Do not travel. If
you must travel...have a winter survival kit with you. If you get
stranded...stay with your vehicle.

&&

$$

IAZ001-012-020-MNZ080-097-098-NEZ014-231815-
/O.UPG.KFSD.BZ.A.0001.170224T0000Z-170225T0600Z/
/O.NEW.KFSD.BZ.W.0001.170224T0000Z-170225T0000Z/
Lyon IA-Sioux-Plymouth-Murray-Pipestone-Rock-Dakota-
414 AM CST Thu Feb 23 2017

...BLIZZARD WARNING IN EFFECT FROM 6 PM THIS EVENING TO 6 PM CST
FRIDAY...

The National Weather Service in Sioux Falls has issued a Blizzard
Warning, which is in effect from 6 PM this evening to 6 PM CST
Friday. The Blizzard Watch is no longer in effect. 

* TIMING...A possible mix of rain and snow this afternoon will
  change to all snow by early this evening. Snow will continue
  heavy at times Thursday night and Friday morning, before
  gradually tapering off Friday afternoon.

* ACCUMULATIONS...Storm total snow accumulations averaging 6 to 12
  inches are likely, with the heaviest amounts expected south of
  Highway 18 in northwest Iowa and extreme southeast South Dakota.

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 35 mph tonight and Friday, with gusts to near 40 mph at
  times. Visibility will be reduced to less than a quarter mile at
  times, especially while snow is falling.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Blizzard Warning means severe winter weather conditions are
expected or occurring. Falling and blowing snow with strong winds
and poor visibilities are likely. This will lead to whiteout
conditions...making travel extremely dangerous. Do not travel. If
you must travel...have a winter survival kit with you. If you get
stranded...stay with your vehicle.

&&

$$

IAZ002-003-013-014-021-022-MNZ081-089-090-231815-
/O.UPG.KFSD.BZ.A.0001.170224T0000Z-170225T0600Z/
/O.NEW.KFSD.BZ.W.0001.170224T0000Z-170225T0600Z/
Osceola-Dickinson-O'Brien-Clay IA-Cherokee-Buena Vista-Cottonwood-
Nobles-Jackson-
414 AM CST Thu Feb 23 2017

...BLIZZARD WARNING IN EFFECT FROM 6 PM THIS EVENING TO MIDNIGHT
CST FRIDAY NIGHT...

The National Weather Service in Sioux Falls has issued a Blizzard
Warning, which is in effect from 6 PM this evening to midnight
CST Friday night. The Blizzard Watch is no longer in effect. 

* TIMING...A possible mix of rain and snow this afternoon will
  change to all snow through this evening. Snow will continue
  heavy at times Thursday night and Friday, before gradually
  tapering off Friday evening.

* ACCUMULATIONS...Storm total snow accumulations averaging 8 to 12
  inches are likely, with some higher amounts possible.

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 35 mph tonight, with gusts to near 45 mph at times late
  tonight into Friday. Visibility is expected to be reduced to
  less than a quarter of a mile at times, especially while snow is
  falling.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Blizzard Warning means severe winter weather conditions are
expected or occurring. Falling and blowing snow with strong winds
and poor visibilities are likely. This will lead to whiteout
conditions...making travel extremely dangerous. Do not travel. If
you must travel...have a winter survival kit with you. If you get
stranded...stay with your vehicle.

&&

$$

IAZ032-231815-
/O.UPG.KFSD.WS.A.0003.170224T0000Z-170225T0600Z/
/O.NEW.KFSD.BZ.W.0001.170224T0000Z-170225T0600Z/
Ida-
414 AM CST Thu Feb 23 2017

...BLIZZARD WARNING IN EFFECT FROM 6 PM THIS EVENING TO MIDNIGHT
CST FRIDAY NIGHT...

The National Weather Service in Sioux Falls has issued a Blizzard
Warning, which is in effect from 6 PM this evening to midnight
CST Friday night. The Winter Storm Watch is no longer in effect. 

* TIMING...A possible mix of rain and snow this afternoon will
  change to all snow through this evening. Snow will continue
  heavy at times Thursday night and Friday, before gradually
  tapering off Friday evening.

* ACCUMULATIONS...Storm total snow accumulations averaging 8 to 12
  inches are likely, with some higher amounts possible.

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 35 mph tonight, with gusts to near 45 mph at times late
  tonight into Friday. Visibility is expected to be reduced to
  less than a quarter of a mile at times, especially while snow is
  falling.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Blizzard Warning means severe winter weather conditions are
expected or occurring. Falling and blowing snow with strong winds
and poor visibilities are likely. This will lead to whiteout
conditions...making travel extremely dangerous. Do not travel. If
you must travel...have a winter survival kit with you. If you get
stranded...stay with your vehicle.

&&

$$

IAZ031-231815-
/O.UPG.KFSD.WS.A.0003.170224T0000Z-170225T0600Z/
/O.NEW.KFSD.BZ.W.0001.170224T0000Z-170225T0000Z/
Woodbury-
414 AM CST Thu Feb 23 2017

...BLIZZARD WARNING IN EFFECT FROM 6 PM THIS EVENING TO 6 PM CST
FRIDAY...

The National Weather Service in Sioux Falls has issued a Blizzard
Warning, which is in effect from 6 PM this evening to 6 PM CST
Friday. The Winter Storm Watch is no longer in effect. 

* TIMING...A possible mix of rain and snow this afternoon will
  change to all snow by late this evening. Snow will continue
  heavy at times Thursday night and Friday morning, before
  gradually tapering off Friday afternoon.

* ACCUMULATIONS...Storm total snow accumulations averaging 6 to 12
  inches are likely, with the heaviest amounts expected south of
  Highway 18 in northwest Iowa and extreme southeast South Dakota.

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 35 mph tonight and Friday, with gusts to near 40 mph at
  times. Visibility will be reduced to less than a quarter mile at
  times, especially while snow is falling.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Blizzard Warning means severe winter weather conditions are
expected or occurring. Falling and blowing snow with strong winds
and poor visibilities are likely. This will lead to whiteout
conditions...making travel extremely dangerous. Do not travel. If
you must travel...have a winter survival kit with you. If you get
stranded...stay with your vehicle.

&&

$$

SDZ050-057-058-063-064-231815-
/O.UPG.KFSD.BZ.A.0001.170223T1800Z-170225T0000Z/
/O.NEW.KFSD.WS.W.0003.170223T1800Z-170224T1800Z/
Gregory-Brule-Aurora-Charles Mix-Douglas-
414 AM CST Thu Feb 23 2017

...WINTER STORM WARNING IN EFFECT FROM NOON TODAY TO NOON CST
FRIDAY...

The National Weather Service in Sioux Falls has issued a Winter
Storm Warning for heavy snow and blowing snow, which is in effect
from noon today to noon CST Friday. The Blizzard Watch is no 
longer in effect. 

* TIMING...Snow will spread into the area by midday today,
  becoming heavy at times this afternoon and evening. Snow should
  diminish through Friday morning.

* ACCUMULATIONS...Storm total snow accumulations averaging 5 to 10
  inches are likely, with the heaviest amounts expected near the
  Missouri River Valley.

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 30 mph tonight and Friday, with gusts to near 35 mph at
  times. Visibility will be reduced to less than a half mile at
  times, especially while snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for heavy snow and blowing snow means
severe winter weather conditions are expected or occurring. 
Significant amounts of snow are forecast that will make travel
dangerous...and visibilities will be limited further due to strong
winds blowing snow around.  Only travel in an emergency.  If you
must travel...keep an extra flashlight...food...and water in your
vehicle in case of an emergency.

&&

$$

SDZ059-231815-
/O.UPG.KFSD.BZ.A.0001.170224T0000Z-170225T0000Z/
/O.NEW.KFSD.WS.W.0003.170223T1800Z-170224T1800Z/
Davison-
414 AM CST Thu Feb 23 2017

...WINTER STORM WARNING IN EFFECT FROM NOON TODAY TO NOON CST
FRIDAY...

The National Weather Service in Sioux Falls has issued a Winter
Storm Warning for heavy snow and blowing snow, which is in effect
from noon today to noon CST Friday. The Blizzard Watch is no 
longer in effect. 

* TIMING...Snow will spread into the area by midday today,
  becoming heavy at times this afternoon and evening. Snow should
  diminish through Friday morning.

* ACCUMULATIONS...Storm total snow accumulations averaging 5 to 10
  inches are likely, with the heaviest amounts expected near the
  Missouri River Valley.

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 30 mph tonight and Friday, with gusts to near 35 mph at
  times. Visibility will be reduced to less than a half mile at
  times, especially while snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for heavy snow and blowing snow means
severe winter weather conditions are expected or occurring. 
Significant amounts of snow are forecast that will make travel
dangerous...and visibilities will be limited further due to strong
winds blowing snow around.  Only travel in an emergency.  If you
must travel...keep an extra flashlight...food...and water in your
vehicle in case of an emergency.

&&

$$

SDZ055-060-061-065-066-068-069-231815-
/O.UPG.KFSD.BZ.A.0001.170224T0000Z-170225T0000Z/
/O.NEW.KFSD.WS.W.0003.170223T2100Z-170225T0000Z/
Lake-Hanson-McCook-Hutchinson-Turner-Bon Homme-Yankton-
414 AM CST Thu Feb 23 2017

...WINTER STORM WARNING IN EFFECT FROM 3 PM THIS AFTERNOON TO
6 PM CST FRIDAY...

The National Weather Service in Sioux Falls has issued a Winter
Storm Warning for heavy snow and blowing snow, which is in effect
from 3 PM this afternoon to 6 PM CST Friday. The Blizzard Watch 
is no longer in effect. 

* TIMING...A possible mix of rain and snow this afternoon will
  change to all snow by this evening. Snow will continue heavy at
  times tonight, before gradually tapering off Friday morning.

* ACCUMULATIONS...Storm total snow accumulations averaging 5 to 10
  inches are likely, with the heaviest amounts expected near the
  Missouri River Valley.

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 30 mph tonight and Friday, with gusts to near 35 mph at
  times. Visibility will be reduced to less than a half mile at
  times, especially while snow is falling. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for heavy snow and blowing snow means
severe winter weather conditions are expected or occurring. 
Significant amounts of snow are forecast that will make travel
dangerous...and visibilities will be limited further due to strong
winds blowing snow around.  Only travel in an emergency.  If you
must travel...keep an extra flashlight...food...and water in your
vehicle in case of an emergency.

&&

$$

SDZ053-054-231815-
/O.UPG.KFSD.BZ.A.0001.170224T0000Z-170225T0000Z/
/O.NEW.KFSD.WW.Y.0006.170223T2100Z-170224T1800Z/
Sanborn-Miner-
414 AM CST Thu Feb 23 2017

...WINTER WEATHER ADVISORY IN EFFECT FROM 3 PM THIS AFTERNOON TO
NOON CST FRIDAY...

The National Weather Service in Sioux Falls has issued a Winter
Weather Advisory for snow and blowing snow, which is in effect 
from 3 PM this afternoon to noon CST Friday. The Blizzard Watch is
no longer in effect. 

* TIMING...Snow will spread into the area early to mid afternoon,
  then continue through tonight. Snow should diminish through
  Friday morning. 

* ACCUMULATIONS...Storm total snow accumulations averaging 2 to 5
  inches are expected.

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 30 mph tonight and Friday, with gusts to near 35 mph at
  times. Visibility will be reduced to a half mile or less at
  times, especially while snow is falling.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for snow and blowing snow means that 
visibilities will be limited due to a combination of falling and 
blowing snow. Use caution when traveling...especially in open 
areas.

&&

$$

SDZ052-231815-
/O.UPG.KFSD.BZ.A.0001.170223T1800Z-170225T0000Z/
/O.NEW.KFSD.WW.Y.0006.170223T2100Z-170224T1800Z/
Jerauld-
414 AM CST Thu Feb 23 2017

...WINTER WEATHER ADVISORY IN EFFECT FROM 3 PM THIS AFTERNOON TO
NOON CST FRIDAY...

* TIMING...Snow will spread into the area early to mid afternoon,
  then continue through tonight. Snow should diminish through
  Friday morning. 

* ACCUMULATIONS...Storm total snow accumulations averaging 2 to 5
  inches are expected.

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 30 mph tonight and Friday, with gusts to near 35 mph at
  times. Visibility will be reduced to a half mile or less at
  times, especially while snow is falling.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for snow and blowing snow means that 
visibilities will be limited due to a combination of falling and 
blowing snow. Use caution when traveling...especially in open 
areas.

&&

$$

SDZ038>040-231815-
/O.UPG.KFSD.WS.A.0003.170224T0000Z-170225T0000Z/
/O.NEW.KFSD.WW.Y.0006.170223T2100Z-170224T1800Z/
Beadle-Kingsbury-Brookings-
414 AM CST Thu Feb 23 2017

...WINTER WEATHER ADVISORY IN EFFECT FROM 3 PM THIS AFTERNOON TO
NOON CST FRIDAY...

The National Weather Service in Sioux Falls has issued a Winter
Weather Advisory for snow and blowing snow, which is in effect 
from 3 PM this afternoon to noon CST Friday. The Winter Storm 
Watch is no longer in effect. 

* TIMING...Snow will spread into the area early to mid afternoon,
  then continue through tonight. Snow should diminish through
  Friday morning. 

* ACCUMULATIONS...Storm total snow accumulations averaging 2 to 5
  inches are expected.

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 30 mph tonight and Friday, with gusts to near 35 mph at
  times. Visibility will be reduced to a half mile or less at
  times, especially while snow is falling.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for snow and blowing snow means that 
visibilities will be limited due to a combination of falling and 
blowing snow. Use caution when traveling...especially in open 
areas.

&&

$$

MNZ071-072-231815-
/O.EXT.KFSD.BZ.A.0001.170224T0000Z-170225T0000Z/
Lincoln MN-Lyon MN-
414 AM CST Thu Feb 23 2017

...BLIZZARD WATCH NOW IN EFFECT FROM THIS EVENING THROUGH FRIDAY
AFTERNOON...

* TIMING...Snow will spread into the area by late this afternoon,
  then continue through tonight. Snow should diminish through the
  day Friday.

* ACCUMULATIONS...Storm total snow accumulations averaging 1 to 4
  inches are expected.

* WIND AND VISIBILITY...Winds will increase from the north around
  25 to 35 mph tonight and Friday, with gusts of 40 to 45 mph at
  times. If the falling snow is heavy enough, visibility could be
  reduced to less than a quarter mile at times, especially while
  snow is falling.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Blizzard Watch means there is a potential for falling and/or
blowing snow with strong winds and extremely poor visibilities.
This can lead to whiteout conditions and make travel very
dangerous.

&&

$$

What forecasters said that day

The local office's own words before this winter storm watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Sioux Falls, SD wrote its last area forecast discussion before this winter storm watch went out at Feb 21, 11:24 AM CST, 4 hours 35 minutes earlier.

Area forecast discussion, Feb 21, 11:24 AM CST, 4 hours 35 minutes before
Area Forecast Discussion
National Weather Service Sioux Falls SD
1124 AM CST Tue Feb 21 2017

.SHORT TERM...(Today and Tonight)
Issued at 413 AM CST Tue Feb 21 2017

Weak ridge axis settling southward across northwest Iowa early
this morning, with moisture from yesterday's rainfall and ideal
radiative cooling enough to produce some patchy shallow fog
near/east of I-29 favoring mainly lower elevation and southerly
upslope locations of the Buffalo ridge. Gradient does continue to
increase gradually through the predawn hours, which should start
to minimize patchy fog coverage and favor gradually more southward
into northwest Iowa. This is similar to treatment by RAP/HRRR
solutions through early morning.

Beyond the fog early morning, today is shaping up to feature
spectacular warmth.  Record temperatures are a certainty for many
locations with very minimal negative impacts on warming toward upper
limits today, with a strong westerly component, minimal cloudiness,
and a drier airmass. Highs looking to reach the lower to mid 70s
through the Missouri River corridor, gradually decreasing toward mid
60s across southwest Minnesota.

Wave riding flattening ridge tonight will glance the far northern
portions of the forecast area. A little mid-level frontal support
for cloud development the latter half of the night heading north
from I-90, but with stout dry layer below, do not expect even any
sprinkles to fall from this cloud layer.  Should again see a fairly
distinct elevation signature to temperatures overnight while in warm
sector, as surface gradient relaxes and decouples for lower
elevations allows for mid to upper 30s, while slightly stronger
winds and higher position in the inversion keeps lower to mid 40s in
play along the Buffalo Ridge and toward south central SD.

.LONG TERM...(Wednesday through Monday)
Issued at 413 AM CST Tue Feb 21 2017

The big story in the medium range forecast continues to be the
abrupt change from record highs to a strong winter storm at the end
of the week.

Wednesday: Shortwave energy zipping through the Northern Plains will
bring an enhancement to mid-level clouds, however soundings continue
to indicate a very dry subcloud layer.  Have kept sprinkles out of
the forecast through the morning.  A frontal boundary passes through
the area early in the day, with cold advection aloft through the
afternoon. Temperatures should still rise into the upper 50s to mid
60s along the highway 20 corridor.

Thursday-Friday: While model spread continues, overnight models have
again trended in different directions, but closer to a bit of a
consensus. The latest ECMWF has lifted slightly further north of
it's previous run, the GFS has again lifted back northward falling
in line and nearly along the mean of the GEFS ensembles. The GEM
remains an outlier, both with the open nature of the initial PV
anomaly, and the lag in timing with the secondary wave on Friday
that will intensify the trough in general.   A closer look at the
GEFS ensembles allows a bit of a QPF base to be established, as very
view members now show the minimal QPF indications of earlier. While
there is still considerable spread in the solutions, there are
several clusters that focus around the deterministic solutions
narrowing in the 25 and 75 percentiles.   The GEFS probabilistic
guidance has also narrowed considerably over the past 24 hours, with
rising and narrowing threshold probabilities indicative of that
growing consensus. So have based the forecast on a blend of the GEFS
mean, EC and to a lesser degree GFS/GEM.  Have generally discounted
the 00Z NAM given it's lower skills at extended portions of it's run.

The real keys to this forecast revolve around depth of an east-west
oriented trough over the Canadian provinces, and stage setter wave
on Wednesday that will help determine northward extent or
development of the low level baroclinic zone on Thursday. The trend
have been to flatten the Canadian trough, allowing Wednesday's wave
slide further north over North Dakota/Minnesota.

Getting down to the details of the forecast, still strong
indications that 700:600 mb frontogenesis will be the initial
forcing mechanism that drives precipitation development through the
day on Thursday.  Of course, we'll be fighting dry air intrusion
from the northeast and east at the low levels, and warming surface
temperatures.  However, all models show that once more intense
precipitation begins to fall, surface temperatures cool to support
more snow. Areas east of I-29 could be more problematic due to the
advection of warmer surface temperatures westward and changeover to
snow may linger until the evening.

Initial frontogenesis will be reinforced by strong synoptic forcing as
a PV anomaly enters the Plains in the evening. As this wave begins
to deepen, forcing should shifts toward the 900:800 MB layer. EC/GFS
continue to push 850mb low track slightly further north overnight
now along a Lincoln to Des Moines to La Crosse into mid-day Friday.
This would keep the large deformation band stalled across and south
of a line from Yankton to Windom.

Winds will complicate matters with this storm, and as the surface
low shifts ever so slightly northward, so will the strongest
gradient winds. Have bumped up sustained winds to 25 to 30 mph
with gusts potential up to 40-45 mph based on low level flow on
the west side of this system. Have placed blowing snow in grids
once snow is on the ground. The initial snow accumulation
projections continue to focus the highest risk of 6" inches south
of Interstate 90, with the greatest risk of 8 or more inches in
parts of Northwest Iowa and adjacent areas of Southern Minnesota
trailing westward along the Missouri River. Further north, a tight
snow gradient may once again form due to the northerly fetch of
dry air. Will not be issuing a winter storm watch at this time,
but one may likely be needed later today.

Next Weekend: High pressure slides in behind this system, and have
lowered daily highs to account for new snow cover. There's still
some potential for light precipitation Monday into Tuesday, but this
continues to be a minor impact.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1123 AM CST Tue Feb 21 2017

VFR will prevail through midday Wednesday.

&&

.FIRE WEATHER...
Issued at 413 AM CST Tue Feb 21 2017

A drying of the airmass today will occur with a better westerly
component to winds. Diurnal mixing will allow humidity levels to
drop to 20 to 25 percent by early to mid afternoon through the
Missouri River corridor, with increasing westerly winds at a gusty
15 to 30 mph. Conditions should stay shy of critical with only an
hour or two of lowest humidity, and winds remaining generally
below 25 mph, but enough to reach a very high rangeland fire
danger through the Missouri River Corridor eastward through
northwest Iowa. While it will be cooler on Wednesday, there will
still be potential for a very high fire danger toward Lower Brule
locations with humidity 25 to 35 percent and northwest winds 15 to
25 mph.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&

SHORT TERM...Chapman
LONG TERM...Dux
AVIATION...MJ
FIRE WEATHER...Chapman
Hazardous weather outlook, Feb 21, 4:12 AM CST, 11 hours 47 minutes before
Hazardous Weather Outlook
National Weather Service Sioux Falls SD
412 AM CST Tue Feb 21 2017

IAZ001>003-012>014-021-022-MNZ071-072-080-081-089-090-097-098-
SDZ038>040-052>056-059>062-067-221015-
Lyon IA-Osceola-Dickinson-Sioux-O'Brien-Clay IA-Cherokee-
Buena Vista-Lincoln MN-Lyon MN-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-Beadle-Kingsbury-Brookings-Jerauld-Sanborn-Miner-
Lake-Moody-Davison-Hanson-McCook-Minnehaha-Lincoln SD-
412 AM CST Tue Feb 21 2017

This Hazardous Weather Outlook is for portions of northwest Iowa,
southwest Minnesota, central South Dakota, east central South
Dakota, and southeast South Dakota.

.DAY ONE...Today and Tonight

Patchy dense fog will be possible through the early morning hours.
Visibilities under one mile may be possible, especially across
areas of southwest Minnesota and adjacent areas of Iowa and South
Dakota.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

A strong storm system is expected to enter the Plains by Thursday
bringing accumulating snow to the region. At this time, a band of
moderate to heavy snow accumulations greater than six inches will
be possible. However, the track of this storm is still uncertain
and this could impact the location of heavy snow amounts. Continue
to monitor your local forecast.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

IAZ020-031-032-NEZ013-014-SDZ050-057-058-063>066-068>071-221015-
Plymouth-Woodbury-Ida-Dixon-Dakota-Gregory-Brule-Aurora-
Charles Mix-Douglas-Hutchinson-Turner-Bon Homme-Yankton-Clay SD-
Union-
412 AM CST Tue Feb 21 2017

This Hazardous Weather Outlook is for portions of northwest Iowa,
west central Iowa, northeast Nebraska, south central South
Dakota, and southeast South Dakota.

.DAY ONE...Today and Tonight

Gusty winds and near record temperatures will lead to very high
fire danger risks this afternoon along the Missouri River Valley.
Outdoor burning should be avoided and extra caution with off road
vehicles.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

A strong storm system is expected to enter the Plains by Thursday
bringing accumulating snow to the region. At this time, a band of
moderate to heavy snow accumulations greater than six inches will
be possible. However, the track of this storm is still uncertain
and this could impact the location of heavy snow amounts. Continue
to monitor your local forecast.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

Nearby

Winter Storm Watches in South Dakota, 2017Winter Storm Watches in Iowa, 2017Winter Storm Watches in Minnesota, 2017Every winter storm watch in 2017

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.